Grinding-wheel-balancing device



T. LARSSON.

GRINDING WHEEL BALANCING DEVICE.

APPLICATION FILED FEB. 9, 1918.

1,352,005. Patented Sept. 7, 1920.

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THURE 114388011, OF WORCESTER, MASSACHUSETTS, A

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Specification of Letters Patent. Patented Sept. 7, 1920.

Application filed February e, 1918. Serial in). 210,103.

To all'whom it may concern:

Be it known that I, THURE LARssoN, a citizen of the United States of America, residing at Worcester, in the county of Worcester and State of Massachusetts, have inventedcertain new and useful Improvements in Grinding Wheel Balancing Devices. of which the following is a full, clear, and exact specification. a

My invention relates to balancing devices and more particularly to an abrasive grindwheel having adjustable means associated therewith Y tially or after changed.

I In the grinding art involving the use of rapidly rotating abrasive wheels it has heretofore been expensive and difiicult to balance these odies and to maintain themin balthe center of gravity has ance as they become worn away in use. An abrasive Wheel is ordinarily made by molding a'mixture of abrasive grain and a binding medium and heat-treating the same to form a hard wheel mass. Because of the necessarily crude and'somewhat inaccurate methods of manufacture emplbyed, the ordinary wheel is inherently in out-of-balance condition. Of the various methods heretofore practised, the most popular has involved boring a hole in the light side of a wheel, filling it with lead and thereafter drilling out portions of this lead to effect a fine balance. Such a procedure however involves considerable expense and the employment of numerous 'skilled men and is' quite unsatisfactory for balancing many types of abrading wheel. On the otherhand, a wheel thus permanently balanced soonbecom'es unbalanced when the outer abrasive surface has been worn away and it is necessary to bring the wheel back into true condition to prevent imperfect grinding results as well as danger of breakage, hence the operation of balancing must be again carried out.

rious constructions have been devisedin past to overcome these diificulties,.'but they have remained r unaecepted by grinding as notuneeting the owing to'suc objections as lackof simplicity in design, expensiveness of manufacture or of the balancin operation and the incon-v veniences and difii culties of readjusting the balance after the wheel has becomeworn.

It is, therefore, the ma n object of my in for balancing the wheel either inicompanylng specification and and the

vention to overcome the difficulties associated with former grinding wheel balancmg devices and to provide a construction which is-simple in design andeasily manufactured and may be readily assembled and adjusted quickly and without difiiculty by ssrenon 'ro nonron comm,

relatively unskilled workmen to effect balancin of the wheel when first manufactured as we 1. as after the center of gravity has changed. I

A further object is to provide a separate and removable device which may be applied to a wheel of standard shape'without changing the wheel in any way and which may be transferred from one wheel to another as is expedient. 7

Astill further object is to utilize a heretofore unused inner peripheral portion of the grinding wheel surface to hold and to conceal the balancing means and by using two of the devices, preferably on opposite sides of the wheel, to adjust them relative to each other to produce an whether the out-of-ba'lance condition is large or small. a I

Further objects will be apparent from the following disclosure as set forth in the acthe claims appended thereto. p

In the drawings, in which like reference numerals indicate like parts Figure 1 isa cross section on a vertical line of the grinding wheel. shown in Fig. 2;

Fig. 2 is a phantom perspective View of a grinding wheel carrying two balancing rings' therein. s

In the an inner wheel for practice of my'invention, I utilize peripheral surface of a grinding supporting a balancing mass and hold such mass. in any desired position by means which frictionally engages or clamps against the 'inner'surface. To this end, I may employ an unbalanced device comprising an expansible member adapted to be inaccurate static balance,

sorted within and engage the wheel periphery, and this device may be circularinshape, preferably hollow in the formof a ring, adj ustable in size and capable of;clam ing and remaining in place against the wheel. In order to obtain a fine precision effect in balancing, I prefer to employ two of these devices, one movable relative to the other, whereby their centers ofgravity may be tated todesired positions,

ture 2 therethrough for fastening the Wheel to a spindle and, in the form being described, annular grooves 3around the splndle aperture on the disk faces 4 of the wheel, These annular grooves are normally providedjn order that the flanges which clamp the wheel to the spindle, may be counterslink below the outer disk surfaces of the wheel. A small space is ordinarily left between these flanges and the outer 'portionof the groove 3, hence I am enabled to utilize this annular space for the purpose of balancing the wheel.

In its preferred form, the balancing device may comprise an annular strip or ring 5 of preferably resilient metal, which may be adjusted 'to a slightly shorter diameter than that of groove 3. This strip 5 embodies in its construction a weight 6 made, for example, of lead or other suitable material, and preferably removably fastened to the strip, as by means of rivets 7. In order that the balancing ring may be fastened within the annular groove of the wheel, this ring 5 is caused to engage the wheel surface frictionally with considerable pressure, "and may be made of material of suflicient resiliency to hold itself in place without further outside means. I however prefer to utilize a positively acting clamping device in order to prevent accidental removal of the balancer. To this end, I may utilize a turn-buckle construction, such as illustrated in the drawing, comprising a screw threaded member 8 having righthanded screw threads on one end and lefthanded threads on the other and a central portion 9 adapted to be engaged by a wrench or other means for turning the same. As illustrated, this central portion may be considerabl enlarged and have small radially dispose hole 10 therein which may be engaged by a tool having a cylindrical or rod shaped end adapted to be inserted in the hole. The two ends of the ring may be provided with upturned flanges 12 and 13, the same properly screw threaded to correspond with the threads of the turn-buckle.

By means of this construction, it is therefore seen that the rings, which may be made of resilient metal, may be expanded into close frictional engagement with the stone and its removal under the normal stresses of the grindingoperation prevented. In this sim lified form of my invention, the ring is ma e to fit a particular wheel, and it is necessary to provide different rings for different sized grinding wheels depending, of course, upon the diameter of the groove in which the ring is to be fitted. Furthermore it is also obvious that the ring may be fastened to the stone upon any inner circumferential surface at any desired location thereon as may be provided for this purpose, although, as previously stated, it is desirable to utilize the standard shaped wheel as now constructed.

In order to balance a grinding wheel it is, therefore, merely necessary to mount the wheel on a balancing stand, insert a ring of the proper size within the annular groove 3 on one side. of the wheel, and a similar ring within the groove on the other side and thereafter rotate thetwo rings relative to each other until their joint center of gravity is opposite the heavy point of the wheel and the out-of-balance condition is compensated, after which the turn-buckles are set and the rings are forcibly clamped in position In the wheel, shown in Fig. 2, it is clear that the lower portion of the wheel is lightest. Since the two weights have, in the form illustrated, greater masses than needed to balance the heavy side of the wheel, they are adjusted equally in opposite directions toa ward a diameter at right angles to a line between the heavy and light ortions of the wheel, until balance is effected. When thereafter the abrading surface of the wheel has become worn away, it is merely necessary to mount the wheel on suitable bearings and adjust the rings to new positions, as may readily. be determined by observation of the wheel action during rotation.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. A wheel balancing device comprising a balancing member having its center of gravity remote from its normal axis of rotation and means for engaging and clamping against an inner peripheral surface of the wheel to hold said member in a balancing position.

2. A wheel balancing device comprising a member having its center of gravity distant from its normal rotative axis, said member having an expansible portion adapted to engage and frictionally clamp against an inner peripheral surface of an unbalanced wheel to hold the device in place while being rotated normally.

3. A wheel balancing device comprising an expansible ring having its center of gravity remote from its axis and means to expand the ring into frictional contact with an inner periphery of a wheel.

4. A wheel balancing device comprising a split ring having its center of gravity apart from its rotative center and a turn-buckle connecting its free ends adapted to expand the ring into engagement with an inner peripheral surface of a grinding wheel.

5. A wheel balancing device comprising a split ring of bendable material, a weight on its inner surface, inwardly projecting flanges on its free ends, one having a right hand and the other a left hand screw thread, and a screw threaded adjusting member operatively engaging said threaded flanges,

adapted to expand or contract said ring ter of gravity apart from its rotative center and means on the ring to clamp it adjustably against a peripheral surface of the wheel in any position for balancing said wheel.

8. In combination, an unbalanced grinding wheel having an inner peripheral surface, a balancing ring adapted to engage said inner surface and means for clamping said ring thereagainst in any position to balance said wheel.

9. In combination, an unbalanced grinding wheel having an inner peripheral surface, an expansible ring engaging said surface and having a weighted portion for balancing the Wheel and means for adjustably expanding the ring to hold it frictionally in position.

10. In combination, a grinding wheel, comprising an unbalancer abrasive body having inner peripheral faces on opposite sides thereof, an expansible ring engaging each peripheral face and having a weighted portion so adjusted in position relative to the other ring as to balance the wheel, and means on each ring to clamp it firmly in place against the inner wheel face.

l1. In-combination, an unbalanced grinding wheel having an inner peripheral surface, two expansible members, a balancing weight on each and means, comprising a turnbuckle, on each member to expand it firmly against said surface in a desired location, whereby the two weights may be adjusted relative to the heavy portion of the wheel to effect a fine balance.

Signed at Worcester, Massachusetts, this 6th day of F6bI., 1918.

THURE LARSSON. 

